Skimming the NACO PowerPoint files here:
I came across the following instruction: if the material for the "Other
Distinguishing Characteristic of the Work" (RDA 6.6) and "...Expression"
(RDA 6.12) is a corporate body, record that body in the 373 field, not the
381.  (See "Describing Works and Expressions," slides #68, 70, and 90.)  I
don't recall encountering this directive before.  To illustrate using an
example from the MARC site:

 130 #0 $a Research paper (South African Law Commission)
 381 ## $a South African Law Commission $2 naf
  - vs. -
 130 #0 $a Research paper (South African Law Commission)
 373 ## $a South African Law Commission $2 naf

What's the reasoning behind this?  The semantics of both RDA elements line
up with the 381 (<>); the field
also employs a $2 like the 373 (<>).  Is the source vocabulary
for the $2 the issue?  The 381 $2 points to the subject code list (which
includes the NAF) and the 373 $2 to the name and title code list (which
also includes the NAF).  The DCM Z1 and LC MARC Supplement are silent on
the matter as far as I can tell; the same for the "MARC 21 Encoding to
Accommodate..." cheat sheet (<>)
updated earlier this year.


Mark K. Ehlert                 Minitex
Coordinator                    University of Minnesota
Digitization, Cataloging &     15 Andersen Library
  Metadata Education (DCME)    222 21st Avenue South
Phone: 612-624-0805            Minneapolis, MN 55455-0439

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the swift course of time." -- Shakespeare, "Two Gentlemen
of Verona," Act I, scene iii